Brake lining and process of making same



it;fisra'F ATENT ore! SUMNER SIMIESON, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE RAYBESTOS 00.. OF BRIDGEPOR-T, CONNECTICUT, A CORPORATION OF CONNECTICUT.

BRAKE LINING AND PROCESS OF MAKING SAME,

harness.

No Drawing.

the like.

Among the salient objects of the present invention are to provide a brake lining which can be made from unwoven felted asbestos fibre, the fiber being united into a compact, substantially homogeneous and uniform mass, primarily by means of a comminuted binder; to provide a product of the character referred to, which is uniform in character and uniform in density throughout its Wearing surface and to substantial depth of the latter; to provide a product, the essential body portion of which may be made of short asbestos fiber united through the medium of a comminuted binder; to provide a product of the above character which can be formed to micrometer measurements, both as regards its Width and thickness; to provide a product having the required oo-efficient of friction, which has a maximum wearing resistance and is capable of withstanding high temperatures Without physical or chemical change; to provide a product which can be made of unspun short fiber, to which may be added the dust or screenings of said fiber, united and held into a compact and relatively solid mass, substantially by the binding action of a material, comminuted or granular when dry; to provide a preformed asbestos or other suitable fibrous sheet which may be formedout of unwoven felted short fibre, and out of which the linings may be stamped or out either before or after saturation, of the sheet with the binder; to provide a process of making the above product which eliminated the expensive and numerous operations necessary in making a woven lining, andwhich permits of the use of the cheapest. portion of the fiber,-which forms a product having 'a uni= form character and density, not possible in the fibrous linings of the prior art; to pro vide a process in which the material left Specification of Letters Patent. Patented MIa 2, 1922, Application filed September 19, 1917. Serial No, 192,231.

I after cutting or stamping out the linings can be ire-treated to make'a new sheet, thus reducing the waste material to a minimum; and 1n general to provide an improved product and process of the character referred to.

In brake linings for motor vehicles and the like the following'are desirable, if not essential, characteristics which should be inherent in a good brake lining.

1. The coefficient of friction should be sufiiciently high to meet all requirements.

2. The lining should have a high Wear resisting' and heat resisting ability,

3. The lining should be of uniform character and density so'that even if the exposed surface wears away, there will at all times bea uniform wearing surface.

4. The lining should be as free as possible from fibers which serve only as binders and are not themselves capable of standing abrasion or heat such as cotton, hemp or sisal fibers and paper.

5. It is desirable to use as many short fibers as possible for the reason that the long fibers are relatively expensive.

6/ The margin of profit makes it exceedingly advantageous to have the process as economical and simple as possible.

7. The waste stock should be reduced to a minimum.

8. The facing should be a tough, compact mass, free from any tendency to cause a separation of its component parts and free of any tendency to ravel. v

9. The facing'should be capable of being punched or drilled and countersunk for rivet holes without destroying its efficiency.

Asbestos from the mine run consists of relatively long fibers known in the art as crude asbestos, relatively short fibers known in the art as fiber asbestos. The crude asbestos is the only portion that can be utilized for spinning and Weaving; the fiber asbestos cannot beuused for such purpose and by means of a comminuted binder carried during the process of manufacture in a suitable liquid vehicle.

One illustration of the manner in which the process ma be carried out is as follows; The asbestos her or low grade short fiber as it comes from the mine is first ground in a suitable grinding machine or crusher. This ground material is then put into a beater, mixed with water or other liquid solution and beaten into a pulp. The wet pulp is then delivered to a paper making machine and formed into laminated sheets of suitable width and thickness. From there the sheet passes through suitable presses and dryers.

Preferably this sheet is of sufficient width to permit of a series of brake linings being stamped or cut out of its width, although the sheet may be made of any width suitable for meeting the particular requirements. Either before or during the operation of cutting, the sheet is pressed to proper shape.

The brake linings are next impregnated or saturated in suitable dipping tanks with {a binder. This binder may consist of either a suitable vegetable oil or gum or mineral oil and gum or bitumens or a combination of both, the comminuted solid matter being carried in a suitable vehicle such as benzine, benzene, coal tar naphtha, petroleum naphtha, alcohol or amyl acetate or the like, which also serves as a solvent. It is of course desirable that the binder have adhesive properties so as to more firmly unite the asbestos fiber into a compact substantially homogeneous mass and a uniform one.

The saturated or impregnated material is then put into a drying oven, which may ha heated by closed steam coils or otherwise, preferably to a temperature not in excess of 200 E, which drying step drives out the solvent. After treating the product is put into a curing oven, where it is subjected to a higher heat, for example from 250 F. to 500 F., more or less. This step gives the necessary hardness to the lining.

The invention is not, limited to the details of product.

I claim as my invention:

1. A process of making brake linings and clutch facings, which consists in felting unwoven asbestos fiber in sheet form, saturating the felted fiber with a binder of mineral oil and gum contained in a mineral solvent, pressing, drying and curing by heat at a temperature in excess of 250 F., and cutting the lining at a predetermined point.

2. A process of making brake linings and clutch facings which consists in felting unwoven asbestor fiber in sheet form, saturating the felted fiber with an adhesive binder of mineral oil, gum and bitumens in a vehicle solvent to unite the fabric, pressing, drying and curing the material and cutting the lining at a predetermined point.

3. A process of'making brake lining and clutch facings which consists in felting low grade asbestos fiber in an unwoven sheet, saturating the felted fiber with a binder of mineral oil, gum and bitumens in a vehicle solvent, pressing and drying the sheet, curing by heat at a temperature, in excess of 250 F. to produce a uniform texture product and cutting the lining in a predetermined manner.

SUMNER SIMPSON. 

